Ex-Microsoft CEO Steve Ballmer has spent $10 million looking at how the US government spends taxes

Steve Ballmer, the former Microsoft CEO who retired in 2014, has spent more than $10 million (£8 million) on a transparency project that uses US government data to show people where their tax dollars are going.

Judging by Ballmer's comments, it's essentially an easy-to-use database of existing government information.

You could, according to The New York Times, look up how many police officers are employed across the country and compare that against crime rates. Or you could look up parking ticket revenue.

Ballmer told the newspaper he wanted to "figure out what the government really does with the money. What really happens?"

There's a debate in the US about the problem of "fake news" in the wake of president Trump's election, so Ballmer's project is timely.

He has spent more than $10 million on the project in direct funding and grants, according to the newspaper. USAFacts could cost up to $5 million (£4 million) a year, Ballmer added.

He's chosen to use government data and not any third-party data, so no one can accuse him of bias. One challenge he's found from this is that the US government can't legally collect data on how many firearms there are in the US. "I'm shocked!" he said, blaming the US gun lobby for the lack of transparency.